How green can you go?
Scientists are edging closer to this green solution through an EU-funded research project titled 'Bacterial wiring for energy conversion and remediation' (BACWIRE). The first 18 months of the project have already seen microbial fuel cell prototypes able to produce 10 Amps of current per square metre and 80 Watts of power per cubic metre. The bacteria used are naturally able to produce an electric current. Using nanoparticles, the researchers are developing a molecular bridge to connect the bacteria to an electrode. The bacteria themselves are attached to a thin surface, making up a biofilm, and connectivity between them also needs to be optimised. The better the connectivity between the bacteria themselves and between the biofilm and the electrode, the faster electrons can be transferred for better power output. Initial studies have revealed the best conditions, such as acidity levels and temperatures, for the biofilm to work. Researchers have also tested surfaces on which to grow the biofilm, including graphite, and gold and platinum crystals. The have explored gold electrodes as well, using different nanoparticles and molecular linkers between the electrodes and the biofilm. In addition, the team has synthesised and characterised gold nanoparticles used to carry charges between the bacteria within their three-dimensional (3D) network on the biofilm. The scientists are now testing fuel cell prototypes with geometries that they say could easily achieve a power output close to 1 Kilowatt per cubic metre. The ultimate goal of the BACWIRE project is to produce 5 KW per cubic metre. Such a prototype could be invaluable for simultaneous clean energy production and wastewater remediation.